When does breast growth occur?
Breast growth is the visible development of breasts in girls. Breast development is often the first sign of puberty in preteen or teenage girls. It can start anywhere between the ages of 7 and 13. However, breasts actually begin to form before a girl is even born.
While baby girls are still in the womb, a premature milk-duct system is already taking shape. Breast tissue remains somewhat active and changes through the first two years of life. Then, it goes into a dormant period until puberty begins. This preadolescent time is Tanner Stage I when only the nipple is raised. (The Tanner Stages are the most widely used way to describe development of girls and boys during puberty.)
At the start of puberty, breast changes begin after a surge of the hormone estrogen. The timing of this is largely hereditary, as is the rate of growth and final breast size. The first noticeable sign of breast growth is small nickel-sized bumps under the nipple. These are breast buds, which elevate the nipple and areola—the darker skin surrounding the nipple. The areola also enlarges during this time. This is Tanner Stage II. On average, it begins around age 10.
In Tanner Stage III, breasts become slightly larger as glandular tissue develops. There is visible breast tissue that expands outside the areola. However, there is no separation of contour between the breast and areola/nipple complex. In other words, the areola and nipple aren’t raised above the breast. The average age for this stage is 12.5 years. Girls typically begin menstruating between this stage and the next one.
Tanner Stage IV involves continued breast tissue development. The areola and nipple enlarge and form a second mound, which is elevated above the rest of the breast. This usually occurs between ages 13 and 14 years. However, some girls skip this stage and move directly from Tanner Stage III to V.
In stage V, the areola recedes, which eliminates the second mound. The breast contour is now smooth and round with only the nipple elevated above the breast. Doctors consider this to be a mature female breast. The average age for reaching Tanner Stage V is 15. However, breasts can continue to fill out through the late teenage years and even early 20s.
The rate of breast growth and development varies widely and each girl’s experience will be unique. On average, the progression from Tanner Stage II to V takes about 4 to 4.5 years. However, it can be as short as 1.5 years or it can take as long as 6 years.
A girl’s breasts can also grow at different rates. It’s normal for one breast to bud before the other. It’s also normal for one to grow faster than the other. This can lead to breasts being different sizes for a period of time. Usually, breast symmetry will even out as they mature. However, it’s common to have some degree of breast asymmetry as an adult woman.
Routine medical care is an important part of every girl’s life. Regular checkups allow doctors to identify the start of puberty and monitor its progress. If you have any concerns about breast growth or development, talk with your doctor.
What signs and symptoms occur with breast growth?
Breast buds are often tender and sore. As breasts continue to grow, they can cause discomfort. The skin will stretch to accommodate them, which can cause itching. If the stretching happens rapidly, stretch marks can also develop. These lines are a type of scar from the rupturing of collagen and elastin in the skin. As these structural components of the skin heal, the marks can appear darker than your normal skin. This ranges from a pinkish to purplish to dark brownish discoloration depending on your skin tone. With time, they will lighten, fade, and become less noticeable.
If breast pain or other symptoms become bothersome, talk with your doctor about strategies to minimize your discomfort.
What makes breasts grow and develop?
Estrogen is responsible for the start of breast growth. As a girl begins puberty, the ovaries release a flood of estrogen. Estrogen causes fat to accumulate and stimulates breast growth. Together with other hormones, estrogen fuels breast development. Your genes play a major role in determining when puberty and breast growth will start and how it progresses.
What potential complications or problems can occur with breast growth?
Most girls go through breast growth and development without complications. However, problems outside of the normal discomfort can occur.
Possible breast problems include:
- Absent or delayed breast development: The timing of breast growth is highly variable. However, if no breast buds have developed by age 13, doctors consider it to be delayed puberty. In rare cases, the breast bud is missing entirely. More commonly, some girls are simply “late bloomers.” But there can be underlying causes of delayed puberty, including eating disorders and chronic diseases like Crohn’s disease and Turner syndrome.
- Breast asymmetry: About 25% of girls will have breasts that grow asymmetrically with one growing faster than the other. And many adult women have mature breasts that aren’t the same size or shape. Most of the time, this isn’t cause for concern. Padded bras and inserts can help even out their appearance when the difference is noticeable. If breast asymmetry causes significant distress, surgery may be an option to correct the differences. It’s usually necessary to wait until breasts have fully matured before considering this option.
- Breast masses: Breasts can feel lumpy and bumpy as they develop and change with a girl’s menstrual period. If a lump persists, a doctor should evaluate it. It’s highly unlikely to be serious—breast cancer is extremely rare in children and teens. Less than 0.1% of breast cancer cases affect this age group. However, it’s possible to develop benign cysts and other noncancerous changes. Imaging exams can help your doctor tell the difference.
- Macromastia: This is the medical term for unusually large breasts that are disproportionate to a girl’s body. The condition can cause social, emotional and physical distress. Physical problems include back pain and skin irritation. Some girls may also experience abnormal sensations in their arms, such as tingling. These symptoms can limit their participation in physical activities. Physical therapy and a proper bra fitting may help relieve some of the physical symptoms. Breast reduction surgery may be an option once breasts are mature.
Another complication of breast growth is when it happens in boys. The medical term for this is gynecomastia. It occurs when enough tissue is present to form a breast mound. This can range from a prominent breast bud to a fuller mound with an elevated nipple that appears very feminine.
All boys have a small amount of breast tissue. And about half of teenage boys will experience tender nipples and even some prominent tissue during puberty. The tissue should shrink over a couple of years. If it persists, treatment may involve surgically removing the tissue. Like other issues with breast growth, gynecomastia is often hereditary. However, there can be underlying hormonal or endocrine problems. See your doctor for persistent problems with enlarged breast tissue in a boy.
